A method of heat transfer printing and a heat transfer sheet of this kind are disclosed, for example, in U.S. Patent No. 4,650,494. According to this method of heat transfer printing, an excellent monocolor or multicolor image can be formed simply and at high speed on an image receiving sheet to which the image is to be printed, and it is possible to obtain a multicolor image having particularly excellent continuous tone and equal quality to that of a color photograph. The heat transfer sheet to be used for the method of heat transfer printing of this kind is designed so that a dye layer having substantially the same size as the entire shape of the sheet to which the image is to be printed (that is, always constant size irrespective of the size, shape or the like of a portion on which the transferred image is formed) is provided on a substrate film.
However, in the conventional heat transfer sheet, in the case where an image is transferred to an image receiving sheet wherein a portion on which the transferred image is formed is located in a part of the surface of the image receiving sheet (in other words, the image forming portion is disposed locally), the dye layer of the heat transfer sheet is used only for a portion corresponding to the aforesaid image forming portion and other dye layer portions are not used. This is uneconomical, and in addition, the peripheral portion of the formed transferred image is contaminated by the unused portion of the dye layer.
The present invention has been accomplished in order to overcome the aforementioned problem. It is an object of the present invention to provide a method of heat transfer printing, which can minimize occurrence of a wasteful dye layer portion even when the image is transferred to the image receiving sheet whose image forming portion is disposed locally, and the peripheral portion of the transferred image is not contaminated. The present invention further provides a heat transfer sheet used for the method.